std::atomic...ax_explicit(3)

💅 std::atomic_fetch_max, std::atomic_fetch_max_explicit 💅

C++ Standard Libary · page std::atomic...ax_explicit(3) · okay bestie, we’re doing atomic max energy today ✨

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💖 NAME 💖

std::atomic_fetch_max,std::atomic_fetch_max_explicit - std::atomic_fetch_max,std::atomic_fetch_max_explicit

That’s the whole name, no cap: two functions, one maxy atomic moment 🫶

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✨ Synopsis ✨

Defined in header <atomic>:

Defined in header <atomic>
template< class T >

T atomic_fetch_max( std::atomic<T>* obj,
(1) (since C++26)

                    typename std::atomic<T>::value_type arg )
noexcept;
template< class T >

T atomic_fetch_max( volatile std::atomic<T>* obj,
(2) (since C++26)

                    typename std::atomic<T>::value_type arg )
noexcept;
template< class T >

T atomic_fetch_max_explicit( std::atomic<T>* obj,
                             typename std::atomic<T>::value_type
(3) (since C++26)
arg,

                             std::memory_order order ) noexcept;
template< class T >

T atomic_fetch_max_explicit( volatile std::atomic<T>* obj,
                             typename std::atomic<T>::value_type
(4) (since C++26)
arg,

                             std::memory_order order ) noexcept;

So here’s the vibe: it atomically replaces the value pointed to by obj with the result of std::max between the old value of obj and arg. Then it returns the value obj held previously. The operation is performed as if this was executed:

1,2) obj->fetch_max(arg)
3,4) obj->fetch_max(arg, order)

Bestie, warning time: if std::atomic<T> has no fetch_max member (this member is only provided for integral and pointer types except bool), the program is ill-formed. That’s a hard no, not a cute little oopsie 😭

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🎀 Parameters 🎀

• obj — pointer to the atomic object to modify
• arg — the value to std::max with the value stored in the atomic object
• order — the memory synchronization ordering

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🫶 Return value 🫶

The value immediately preceding the effects of this function in the modification order of *obj. Slay, that’s the return value 💖

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🧠 Notes 🧠

Feature-test macro tea ☕:

• __cpp_lib_atomic_min_max — value 202403L; Std (C++26); feature Atomic minimum/maximum

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🍓 Example 🍓

This section is incomplete.

Reason: no example.

It’s giving “placeholder era,” bestie — no example yet 🙈

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👀 See also 👀

• fetch_max (C++26) — atomically performs std::max between the argument and the value of the atomic object and obtains the value held previously (public member function of std::atomic<T>)
• atomic_fetch_min, atomic_fetch_min_explicit (C++26) — replaces the atomic object with the result of std::min with a non-atomic argument and obtains the previous value of the atomic (function template)

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💀 Category 💀

• * Todo no example

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okay bye bestie — this page’s source/version/date footer energy is http://cppreference.com, 2024.06.10, page std::atomic...ax_explicit(3) 💖✨🦋